Breeding Bird Monitoring in Great Lakes National Forests : 1991-2003

Abstract

A total of 132, 134, and 169 stands (1,271 survey points) were surveyed for breeding birds in the Chequamegon, Chippewa, and Superior National Forests, respectively in 2003. Annual surveys have been conducted since 1991 in the Chippewa and Superior National Forests, and since 1992 in the Chequamegon National Forest. Breeding bird surveys in the St. Croix region of Minnesota have been conducted since 1992 on 170 stands (170 points). • We examined trends in relative abundance for 68 bird species in at least one of the four study areas. Fifty-five species in the Chequamegon NF, 52 in the Chippewa NF, 44 in the Superior NF, and 41 in the St. Croix region were tested for population trends. Thirty-six species were also tested for regional trends by combining data from the three national forests. • A total of 192 species/study area trends were calculated (not including regional trends), 98 (51%) of which were significant (P < 0.05). Twenty-five species increased significantly (P < 0.05) in at least one study area and 31 species decreased. • Seven species had significant increasing regional trends and 14 had decreasing trends. Six species had highly significant (P < 0.01) increasing trends in multiple study areas, and nine species had highly significant decreasing trends in multiple study areas. • The percentage of increasing species in each study area ranged from 13% in the Chequamegon NF, to 29% in the St. Croix study area. The percentage of decreasing species ranged from 25% in the Chequamegon NF study area, to 35% in the Chippewa NF. • There were 12 instances where a species wasn’t increasing in a particular study area in 2002 results but is increasing in 2003, and ten instances where a species showed a significant increase in 2002, and isn?t in 2003. Conversely, there were 19 instances where a species wasn’t decreasing in 2002 but is decreasing in 2003, and one instance where a species showed a decrease in 2002 but isn’t in 2003. • Short-distance migrants showed highly significant declines in all study areas. Long-distance migrants showed mixed results, including declines in the Chequamegon and Superior NF’s，an increase in the St. Croix study area，and a stable trend in the Chippewa NF. Permanent residents increased on all study areas except the Chequamegon NF, where they were stable. • Ground nesting birds showed highly significant declines in all study areas, with shrub and sub-canopy nesters increasing in all study areas. Canopy and cavity nesters showed mostly stable trends. Of the five vegetation-type preference guilds tested, lowland coniferous forest birds, deciduous, and mixed forest bird species showed widespread declines on our study areas, and upland coniferous species increased on all study areas except the Chequamegon NF. The early-successional guild showed an increase in the Chippewa NF and declines in the Superior NF and the regional analysis. • Evidence from recent regional studies have demonstrated greater nest predation rates on ground nests near forest/clearcut edges, as well as a significant increase in the creation of forest edges in recent years. Landscape fragmentation and nest predation may be having negative effects on declining ground-nesters such as the Winter Wren, Hermit Thrush, Black-and-white Warbler, Ovenbird, and White- throated Sparrow. • Of the 1445 survey sites in all four study areas, 13.4% have been at least partially harvested since the beginning of monitoring, which is about 1% a year. This harvest rate is comparable to the 4.8% change from mature forest to early- successional types on federally managed forest lands in northeastern Minnesota between 1990 and 1995 (i.e. -1% annual change). • Many of the declining trends that we have detected have been consistent across the years and are not likely due to annual variation. One of the main goals of this monitoring program is to identify species of conservation concern, and species such as the Eastern Wood-Pewee, Winter Wren, Hermit Thrush, Mourning Warbler, Ovenbird, and White-throated Sparrow probably need special management consideration by agencies such as the U.S. Forest Service and state Department of Natural Resources. Although most of these are common species, several are currently well below their estimated RNV values and they may not remain common if their declining trends continue.